1. Field of Art
The invention relates generally to computing a person's cognitive function and, more specifically, to unobtrusive assessment of cognitive function from electronic device usage.
2. Background Art
Cognitive function tests measure a person's cognitive abilities across a broad range of cognitive domains such as memory (working memory, semantic memory, episodic memory), attention, processing speed (visuospatial, symbol substitution), verbal skills, general intelligence, and executive function. Today, cognitive function tests are administered by a trained psychometrician requiring several hours of testing and cannot be repeated more frequently than once per year. The test scores can vary due to a change in the person's cognitive function, due to the subjective nature of the interpretation of the tests, or due to situational factors that may affect an individual on the day of the test.
Brain health is critical to our success as individuals in an increasingly cognitive demanding society. In school aged children and adolescents, brain health is responsible for academic success. In working individuals, brain health leads to improved job performance, and in the elderly it enables autonomy, independence and greater enjoyment from activities.
Cognitive function is a measure of brain health, and factors that affect the brain also affect cognitive function. These factors can be categorized into situational, traumatic, and disease related. Situational factors include lifestyle decisions on diet, social engagement, intellectual stimulation, physical activity, sleep patterns, and stress levels. For example, during periods of high stress, poor sleep, and inadequate physical activity, a person will perform worse on a cognitively demanding task [1]. Unfortunately, there is no known reliable system or method for repeated and regular assessment of cognitive function to inform a person of the harm or benefit that current lifestyle decisions have on their brain health. Repeat cognitive function testing by a psychometrician is neither practical nor reliable when repeated more frequently than once per year because the individual acquires test-taking skills for the test. Similarly, the emergence of online tests available through many application vendors such as BrainBaseline [2] suffer test practice effects that are well documented [3,4] whereby the subject develops test taking skills that increase their scores but do not transfer well to real world activities and undermine the test's sensitivity and specificity to cognitive changes.
Traumatic factors affecting cognitive function include blunt or penetrating head injuries. Unlike situational factors, the effect of traumatic brain injury on cognitive function is not generally reversible. Traumatic brain injury is increasingly recognized as a contributor to cognitive function deficits in players of contact sports. Early detection of changes in cognitive function for contact sport athletes is paramount to their brain health and requires a systemic method to measure cognitive function that is repeatable, reliable, and unobtrusive.
Many diseases are known to affect brain health and cognitive function. The progression of aging into mild cognitive impairment and Alzheimer's disease is of great societal concern because of its rapidly increasing prevalence in an increasingly older society. Today, one in eight older Americans has Alzheimer's disease and Alzheimer's is the sixth leading cause of death in the United States [5]. By 2025, the number of Americans age 65 and older with Alzheimer's disease is estimated to increase 30%, and by 2050 that number is expected to triple, barring any breakthroughs to prevent, slow or arrest the disease [5]. Prior to developing Alzheimer's disease, patients go through a six-year prodromal phase of cognitive decline. The societal burden of mental disease in the elderly is staggering and poised to worsen. A repeatable, reliable, and unobtrusive test of cognitive function is needed to monitor brain health in aging adults to enable early detection and intervention.
Mood disorders include depressive disorders, bipolar disorders, and substance-induced mood disorders. They affect people of all ages and impair multiple cognitive domains [6]. In the United States, mood disorders are among the most common reason for hospitalization in children under 18 [7]. With a 12-month adult prevalence of 9.5% [8], mood disorders are a costly social burden. Mood disorder therapy focuses on the behavioral and mood related facets of the disease to the detriment of the cognitive function deficits. Medications to treat mood disorders can worsen cognitive domains such as memory. The impact of cognitive deficits in a person's school or job performance can be significant, is exacerbated by treatment, and frequently unrecognized due to lack of adequate repeatable, reliable, and unobtrusive measures of cognitive function.
Many other diseases are known to affect brain health and cognitive function. These include neurovascular disorders including multi-infract dementia, hepatic failure with encephalopathy, renal failure, congestive heart failure, and various infectious disease and viral illness to name a few. Individuals with any of these disorders are at risk for cognitive impairment and would benefit from repeatable, reliable, and unobtrusive measures of cognitive function.
The introduction of mobile devices and their broad adoption has revolutionized how society interacts both with each other and with their surroundings. A smartphone today enables a user to make calls, send and receive emails and text messages, find their location on a map or retrieve directions to a destination point, browse the internet, download and play game applications, and a host of other activities. In addition, these smartphones are equipped with accelerometers and gyroscopes that sense the device's acceleration and orientation in 3-dimensions. Processing of the acceleration and orientation signals reveals the user's activity such as whether the person is walking or jogging. Mobile devices encompassing wearable electronic devices such as watches, clothing, and glasses [9,10] are also capable of delivering much of the functionality found in a smartphone.
One company that has leveraged the close interaction of an individual with their mobile device to make behavioral assessments is Ginger.io [11,12]. Ginger.io provides a smartphone application that tracks the number and frequency of calls, text messages, and emails sent, and uses the device's global positioning system (GPS) and accelerometer to infer activity level. The target population for Ginger.io's application is patients with chronic diseases such as diabetes, mental disorders, and Crohn's disease. When a patient deviates from their routine behavior of calling and texting patterns, Ginger.io alerts the individual's caregiver to intervene and assess the situation for noncompliance with medications, inappropriate titration of medications, and other factors that may precipitate a flare-up of the patient's disease. This approach is behaviorally based and does not measure cognitive function but rather changes in behavior that may be attributed to a preexisting disorder flare up.
Recent research supports a close interaction between motion and cognition, largely mediated by interconnections between the cerebellum responsible for motion and areas in the brain such as the prefrontal cortex responsible cognition [13,14]. Sensors in an electronic device, including wearable devices, provide insights into the user's motion and enable detection of irregularities or changes in motion.
What is needed is a method and system to assess cognitive function that is repeatable, reliable, and unobtrusive to an individual.                1. Lieberman H R, Thario W J, Shukitt-Hale B, Speckman K L, Tulley R, Effects of caffeine, sleep loss, and stress on cognitive performance and mood during U.S. Navy SEAL training. Psychopharmacology, 2002, 164:250-261        2. www.brainbaseline.com        3. Ackerman P L, Individual differences in skill learning: An integration of psychometric and information processing perspectives. Psychol Bull, 1987, 102:3-27        4. Healy A F, Wohldmann E L, Sutton E M, Bourne L E, Jr, Specificity effects in training and transfer of speeded responses. J Exp Psychol Learn Mem Cognit, 2006, 32:534-546        5. Alzheimer's Association, 2012 Alzheimer's Disease Facts and Figures. www.alz.org/downloads/facts_figures_2012.pdf        6. Marvel, Cherie L., and Sergio Paradiso. “Cognitive and neurological impairment in mood disorders.” The Psychiatric clinics of North America 27.1 (2004): 19.        7. Pfuntner A., Wier L. M., Stocks C. Most Frequent Conditions in U.S. Hospitals, 2011. HCUP Statistical Brief #162. September 2013. Agency for Healthcare Research and Quality, Rockville, Md.        8. Kessler R C, Chiu W T, Demler O, Walters EE. Prevalence, severity, and comorbidity of twelve-month DSM-IV disorders in the National Comorbidity Survey Replication (NCS-R). Archives of General Psychiatry, 2005 June; 62(6):617-27.        9. http://www.crunchwear.com        10. http://en.wikipedia.org/wiki/Google_Glass        11. www.ginger.io        12. Owen Covington, ‘Virtual nurse’ helps Forsyth Medical Center track diabetics. The Business Journal, May 2013, http://www.biziournals.com/triad/news/2013/05/20/forsyth-medical-center-using-virtual.html        13. Koziol L F, Budding D, Andreasen N, D'Arrigo S, Bulgheroni S, et al. (2013) Consensus Paper: The Cerebellum's Role in Movement and Cognition. Cerebellum: Cerebellum (2014) 13:151-177        14. Jensen E. Teaching with the Brain in Mind, 2nd Edition. Association for Supervision & Curriculum Deve; Revised 2nd edition, 2005        